Fisher 800 c
- Thread starter lanebrain
- Start date
Probably the first thing would be to replace some of the capacitors. The main power supply filter capacitors and the coupling capacitors to the output tube grids are the most important.
The bias rectifier (if there is one, I'm not looking at a diagram) is probably selenium and should be replaced with a silicon plus a resistor.
The controls all should be cleaned with some chemical solvent; there seems to be a consensus here that something called Deoxit is good for that.
After doing all that, adjust the bias and you should be good to go.
The bias rectifier (if there is one, I'm not looking at a diagram) is probably selenium and should be replaced with a silicon plus a resistor.
The controls all should be cleaned with some chemical solvent; there seems to be a consensus here that something called Deoxit is good for that.
After doing all that, adjust the bias and you should be good to go.
audiodon
Addicted Member
lanebrain,
A good starting place if you wish to sling a soldering iron yourself is with a metalbone upgrade kit. Great documentation and decent, though not exceptional, parts. Worth the investment. Find metalbone with a google search.
If you don't want to sling the soldering iron yourself, there are excellent resources on this site for restoration, such as dewickt and NOSvalves.
A good starting place if you wish to sling a soldering iron yourself is with a metalbone upgrade kit. Great documentation and decent, though not exceptional, parts. Worth the investment. Find metalbone with a google search.
If you don't want to sling the soldering iron yourself, there are excellent resources on this site for restoration, such as dewickt and NOSvalves.
Hi Lanebrain,
Reconditioning these is not as daunting as it may first seem.
Start by obtaining a schematic, which are readily available on the Internet, or from someone here or elsewhere.
There are a number of items that must be replaced, others that should be replaced, and some others that are strictly optional.
At the expense of repeating what has been covered in great detail over many years, I encourage you to perform an archive search both here, and over at another site where I (and others) posted regularly on these instruments for many years. In those archived posts you will find detailed part by part recommendations, values, some experiences with different replacement part brands and materials, tube replacements, substitutions and rolling recommendations, and other more esoteric tips as to chassis, faceplate and dial glass cleaning, festoon lamp replacement - and most importantly, what NOT to do.
A vast library of Fisher tube information is only an archive search or two away. It has all you should reasonably need to know to get your 800C working like brand new.
The most important things to remember up front when just starting is to not plug it in and power it on until the minimal items have been checked out and/or repaired, to go very slowly in each phase of restoration, and to undertake "mods" or "upgrades" after first sampling the original circuit, and only one change at a time, so that you can find what you like and don't like.
If you run into specific troubles once you get started, post back and someone is always more than happy to help you through it.
Good luck!
Reconditioning these is not as daunting as it may first seem.
Start by obtaining a schematic, which are readily available on the Internet, or from someone here or elsewhere.
There are a number of items that must be replaced, others that should be replaced, and some others that are strictly optional.
At the expense of repeating what has been covered in great detail over many years, I encourage you to perform an archive search both here, and over at another site where I (and others) posted regularly on these instruments for many years. In those archived posts you will find detailed part by part recommendations, values, some experiences with different replacement part brands and materials, tube replacements, substitutions and rolling recommendations, and other more esoteric tips as to chassis, faceplate and dial glass cleaning, festoon lamp replacement - and most importantly, what NOT to do.
A vast library of Fisher tube information is only an archive search or two away. It has all you should reasonably need to know to get your 800C working like brand new.
The most important things to remember up front when just starting is to not plug it in and power it on until the minimal items have been checked out and/or repaired, to go very slowly in each phase of restoration, and to undertake "mods" or "upgrades" after first sampling the original circuit, and only one change at a time, so that you can find what you like and don't like.
If you run into specific troubles once you get started, post back and someone is always more than happy to help you through it.
Good luck!
Glassweights
Compulsive about tubes
Second the motion on a kit
I am going to second the idea of buying a kit.
I love picking parts and making decisions on price and quality, but this unit has an so many parts that it just ate up way too much time selecting them all.
got any pics?
Dan
I am going to second the idea of buying a kit.
I love picking parts and making decisions on price and quality, but this unit has an so many parts that it just ate up way too much time selecting them all.
got any pics?
Dan
Kits containing detailed information, such as those that Al the Fisher Doc offers (other issues aside), are very good for the novice. With those kits, you are paying for the detailed information and guidance and not so much the parts.
Kits containing just parts, or perhaps with a basic (now virtually public domain) schematic thrown in (like the old VTV kits), are not very good values IMO, except for the very lazy.
The typical reconditioning cost, even using high quality parts like Atoms, Dales, and CDEs, if designer caps are not used, is still around $25. Most kits do not offer better parts quality, and in many instances are worse, than what can be bought from Mouser for a small fraction of the kit cost.
Kits may also not comport well with other service options, such as the SDS cap board. You may find some kit parts useless (and wasted) in those situations.
You're also at the mercy of what the kit designer thinks needs replacing, and at what values. And you're also at the mercy of the kit designer's competence. I've seen supposedly reputable kits specifying totally inappropriate (and unsafe) DC film capacitors as suppressor replacements, where a Y-Class part is required.
There is a lot of information on these instruments all over the Internet at this point, on exactly what needs checking, repairing and replacing. Plenty of options are out there to consider for someone willing to look it up. An hour's worth of research is usually worth the money saved on a kit, and can result in a far more satisfying project result.
At one point about six or eight years ago, I started drafting a comprehensive FAQ/restoration guide for the Fisher tube receiver family, including detailed parts lists and parts brand listening tests and recommendations. But I never finished it. Too much else to do. I guess if I ever did get around to finishing it, it could be a publicly posted "project" on Mouser. One click, and your parts are ordered. But I guess all the Internet kit sellers would have a fit if that happened. Nevertheless, there's still enough specific data posted out there to quickly cobble together exactly what is needed.
